The invention relates to dental occlusion relations for the distances between teeth.
In dental procedures in general and more specifically in orthodontic procedures, a model of a patient""s teeth is required in order to make treatment decisions in, for example, design of braces, crowns, bridges, etc., and to allow monitoring of dental procedures. Of particular importance is a knowledge of the distance and spatial relationship between the teeth on opposite jaws.
Dental procedures requiring knowledge of the position of teeth and the distance between teeth on opposite jaws, generally use models of the teeth, referred to hereinafter as xe2x80x9cdental modelsxe2x80x9d. Typically, plaster dental models are used, which are made by casting plaster into the negative impression made by teeth in an appropriate matrix. Dental models can, however, be made of any convenient material.
However, this approach has a number of major drawbacks. First, in the occluded state it is difficult to see the relation between facing surfaces of opposite teeth of the upper and lower jaws. Second, on moving a tooth, or adding a tooth, or changing the form of a tooth in the dental model, it is not possible to see if the affected tooth affects the occlusion. Third, the information provided by dental models regarding proximity of opposite teeth in opposite jaws is typically no more than whether certain points of opposite teeth make contact, or not, in the occluded state. In order to be able to arrive at an optimal closing of the teeth when changes are made to one or more of the teeth of the dental model, a fairly long and tiresome process of physically modelling the affected teeth is required in order to ensure a good fit between opposite teeth on opposite jaws in the occluded state.
With the advent of powerful computers and advanced computer aided design techniques, it would be expected that three dimensional virtual dental models would help in alleviating the problems encountered with the plaster dental models. Storing a computer virtual dental model on a computer can be achieved xe2x80x9cdirectlyxe2x80x9d by scanning and digitizing the teeth and gums, or xe2x80x9cindirectlyxe2x80x9d by utilizing a plaster dental model or the negative impression. The latter method is disclosed in PCT Application No. PCT/IL 96/00036, Publication No. WO 97/03622, published on Feb. 6, 1997, hereinafter incorporated by reference. However, none of the existing virtual computer dental models provide tools relating to the distance between opposite teeth on opposite jaws.
It is the object of the present invention to provide a method for graphically representing the distance between opposite points, or regions, on the surface of opposite teeth of the upper and lower jaws. The proposed method exploits an existing three-dimensional virtual dental model obtained, directly or indirectly, from actual teeth and associated gums.
The resulting graphical representation of the distance between opposite points, or regions, on the surface of opposite teeth will be termed an xe2x80x9cocclusion mapxe2x80x9d.
The occlusion map comprises colored regions, where each color corresponds to a given distance, or range of distances, between opposite points or regions on the surface of opposite teeth. The occlusion map therefore provides a clear indication of the distance between opposite portions of the surfaces of opposite teeth. The term xe2x80x9ccolorxe2x80x9d used herein includes not only all colors and shades of colors but also black and white and all shades of grey between black and white on a grey scale.
In accordance with the present invention there is provided a method for obtaining a dental occlusion map of a three-dimensional virtual computer model of teeth of upper and lower jaws of a mouth, said occlusion map indicative of distances between opposite regions on facing surfaces of opposite teeth of the upper and lower jaws of the mouth, said method comprising the steps of:
(i) determining said distances between opposite regions on opposite teeth of the upper and lower jaws of the mouth; and
(ii) setting up a correspondence between said determined distances and regions on a mapping surface.
If desired, said mapping surface is a plane, whereby said dental occlusion map is a two-dimensional map of the distances between said opposite regions on said opposite teeth.
Alternatively, said mapping surface is a facing surface of said facing surfaces of opposite teeth of the upper and lower jaws of the mouth.
In accordance with one embodiment, said facing surface belongs to the teeth of said upper jaw, and said lower teeth and lower jaw are transparent.
In accordance with another embodiment, said facing surface belongs to the teeth of said lower jaw, and said upper teeth and upper jaw are transparent.
Preferably, said opposite regions on said facing surfaces of opposite teeth are colored in accordance with a given color scale and wherein each color corresponds to a given distance.
Alternatively, said opposite regions on said facing surfaces of opposite teeth are shaded in accordance with a grey scale and wherein each shade corresponds to a given distance.
If desired, said opposite regions on said facing surfaces of opposite teeth are points.
Further if desired, said regions on said mapping surface comprise at least one pixel.
By one specific application, said occlusion map only shows those distances that are less than one tenth of a millimeter.
By another specific application, said occlusion map only shows those distances that are zero in value.